As to electronic components such as piezoelectric vibrators having a natural resonance frequency, a method where a reactance element is connected to the resonance circuit such as a serial LC resonance circuit or a parallel LC resonance circuit is known as means for changing their zero-phase frequency, that is, the resonance frequency. As such, the resonance frequency range cannot be arbitrarily changed unless the circuit constant of a resonance circuit is changed. Meanwhile, Patent Literature 1 discloses an RC polyphase filer comprising four input terminals for receiving four-phase signals having a phase difference of 90° and a circuit for outputting four-phase signals. In this filer, a quasi-resonant peak voltage is generated using a non-resonant element without a resonance element such as a serial LC circuit, but the resonant peak voltage itself cannot be varied depending on frequency.
Namely, with this type of composite resonance circuit, the resonance frequency range cannot be changed unless the circuit constant of a resonance element or a non-resonant element is changed.    Patent Literature 1: Japanese Patent Kokai No. 2006-319115